Abstract

The recovery of metals from discarded printed circuit boards using environmentally-friendly physical routes is gaining importance. Physical separation of metal values from non-metallic constituents exploits various characteristics of crushed powder such as density, liberation, shape, size, and wettability. However, the generation of fines during grinding/crushing of the printed circuit boards is an unavoidable but essential by-product. The fine fractions are discarded due to the higher amounts of non-metallic fraction and poor separation of metallic values. In this study, the flotation process was studied to separate metallic and non-metallic values without the addition of external additives from the fine fraction of printed circuit boards (< 212 µm). The natural hydrophobic response of plastic and organic matter in fines stabilized the froth without additional reagents. The difference in tapped density for tailing (~ 0.5 g/cm³) and concentrate (~ 2.7 g/cm³) fraction ensures good separation. The metallic fraction increases from 14.3% in the feed to 91.7% in the concentrate. Recovery for metallic values was observed as ~ 72.3% with a purity of ~ 92% and comprised 77.9% Cu, 8.3% Sn, and 5.5% Pb.

Graphical Abstract

中文翻译：

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通过浮选处理废弃的印刷电路板细料

摘要

使用环保的物理路线从废弃的印刷电路板中回收金属的重要性日益提高。金属值与非金属成分的物理分离利用了压碎粉末的各种特性，例如密度，游离度，形状，尺寸和润湿性。然而，在印刷电路板的研磨/粉碎过程中产生细粉是不可避免的，但是必不可少的副产物。由于较高数量的非金属级分和较差的金属价位而将细级分丢弃。在本研究中，研究了浮选工艺以分离金属和非金属值，而无需从印刷电路板的细小部分（<212 µm）中添加外部添加剂。细粉中塑料和有机物的天然疏水反应可稳定泡沫，而无需其他试剂。拖尾丝锥密度的差异（〜0.5 g / cm³）和浓缩物（〜2.7 g / cm ³）部分可确保良好的分离。金属含量从进料中的14.3％增加到精矿中的91.7％。观察到金属值的回收率为〜72.3％，纯度为〜92％，并且包含77.9％的Cu，8.3％的Sn和5.5％的Pb。

图形概要